Not anchor worm, but a very common (in tetras like cardinals, rummynose and emperors) parasite known as Dermocystidia/Dermosporidia. You can find it in Dieter Untergassers book from TFH on "Fish Diseases".
There is very little information on what this is and the life cycle of it, but in general it is not a cause for concern in Aquarium fish and no treatment is known. Dermocystidia and Dermosporidia are basically the same thing.... a spore/cyst producing fungi or similar that in freshwater fish causes no major fatalities (unless the cysts are in the gills)..... but they have been recorded in molluscs, like oysters, where they can cause problems. (I think from memory, Dermosporidium is the Genus name for some of the marine Dermocystidia that have been described)
Strange that there is very little info on the net....... but if no one puts it up on the net, then it is not there to view.